media: cx231xx-dvb: fix memory leak in dvb_fini()

In dvb_init(), dev->dvb is allocated by kzalloc.
Therefore, it must be freed being set to NULL.
Signed-off-by: Young Xiao <92siuyang@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/cx231xx/cx231xx-dvb.c

@@ -1147,6 +1147,7 @@ static int dvb_fini(struct cx231xx *dev)
 
 	if (dev->dvb) {
 		unregister_dvb(dev->dvb);
+		kfree(dev->dvb);
 		dev->dvb = NULL;
 	}